Toe actuated safety device for automatic doors



April 24, 19 N. T. WILLIAMS TOE ACTUATED SAFETY DEVICE FOR AUTOMATICDOORS Filed Feb. 4, 1960 5 M [WW 3 g fl 4 1 1 M a a v MNm pm: 4 a i 1 04 a 1 Wm M E m MW.-

EXIT 42 2000 IN VEN TOR.

United States Patent 3,031,546. TOE ACTUATED SAFETY DEVICE FOR AUTOMATICDOORS Nathan T. Williams, 1642 35th St., Sacramento, Calif. Filed Feb.4, 1960, Ser. No. 6,727

1 Claim. (Cl. Mill-61.62)

The present invention relates generally to safety dc vices for use withswinging doors.

More particularly, it relates to safety devices which check the movementof power actuated swinging doors when such doors encounter anobject intheir path. This application is a continuation-in-part of myapplicationSerial No. 806,190, filed April 13, 1959.

The present invention is intended tobe used with such automatic swingingdoor operators and systems as is disclosed, for instance, in the UnitedStates Letters Patent No. 2,739,808, issued to Martin Carlson on March27, 1956.

Automatic swinging doors of the above mentioned type are ordinarilyarranged to swing open when a person by stepping on an approach matcloses a switch contained therein or alternatively closes a contactswitch, .for instance, located at an appropriate position on the door.The door thus opened will remain open so long as a second switch isclosed, the second switch being located, for instance, within an exitmat.

Some systems, such as the one disclosed in the Carlson patent mentionedabove, are so arranged that if a person steps upon the exit mat beforethe approach mat is actuated, the door will not swing; but once such adoor starts to swing, if the person remains upon the approach mat, itwill continue to swing to its fully open position even though a personsubsequently steps upon the exit mat. A serious injury mayoccur,therefore, should a person venture into the path of the door after ithas started to swing. This is especially important in supermarkets andthe like where small children may play unattended while their mothersfocus'their attention on shopping. The present invention solves thedifficulty, removes the risk, and provides safety where heretofore therewas some danger of serious harm.

The principal object of the present invention is to provide a novelsafety mechanism which will check the movement of the swinging door ifthe door encounters an object in its path of movement.

Another object is to provide a novel safety switch which includesmechanism positioned along the bottom rail of the door in such fashionthat contact along any part of the rail will actuate the switch andcheck the movement of the door.

A further objcct'is to provide a safety device which accomplishes theabove and which will permit a stopped door to resume its swingingmovement to fully opened position, once the obstructing object has beenremoved.

Yet another object is to provide a safety device having the abovecharacteristics and which is inexpensive to manufacture and easilyinstalled.

Other objects and advantages of the present invention will becomeapparent from the following description of a preferred embodimentthereof which is illustrated in v the accompanying drawings wherein:

FIG. 1 is a front view of a door on the exit side with a safety deviceincorporating the presentinvention installed thereon;

FiG. 2 is a large scale transverse sectional view through the lowerportion of the door and may be considered as taken substantially alongline 22 of FIG. 1 looking in the direction of the arrows; and

FIG. 3 is an electrical circuit diagram incorporating the invention.

Reference to FIGS. 1 and -2 shows the manner of ice mounting the safetydevice on a swinging door. The door designated generally by the numeralis of standard construction and is adapted to swing on a floor spindle12. The door operator will not be described here in detail because itmay be any of several types, one of which forms the subject matter ofthe previously referred to patent. Generally, the door 10 will turn withthe floor spindle 12 which is rotated by a fluid motor 11: when a pumpunit 13 connected thereto is electrically actuated. The pump unit isactuated by a control system 15 when a switch is closed by a person,preparatory to passing through the door 10, stepping upon the approachmat 14. Closing of the approach mat switch keeps the pump motoroperating until the person steps off the approach mat and upon the exitmat 16. Thereafter the pump motor keeps running because of the closedexit mat switch until i the person steps off the exit mat, whereupon thepump motor stops and the door swings to closed position.

As previously'mentioned, if a person steps upon the exit mat first, thecontrol-system 15 will not cause the door to swing, but once a swingingcycle has been started, it will continue so long as a person is uponeither of the mats, irrespective of any objects coming. into its path.To prevent any injury to persons and objects from the impact of theswinging door 10', the present invention provides a safety device 17which checks the movement of the door 10. The safety device includes aswitch 18 comprised of a switch body 20 having one of its ends connectedto a threaded barrel 22, the barrel extending through an opening nearthe center of the bottom door rail 24 and being secured to the rail by apair of clamping nuts 26 and 28. A switch plunger 30 extends centrallythrough the'barrel 22, the plunger being spring biased outwardly andaway from the switch body 20. As

shown in FIG. 3, the contacts are of the single pole, single throw,normally closed type. The switch plunger 30 has a relatively largerbutton head 32 so that the area subject to contact is large enough toprovide good wear resistance in service. A section of extruded aluminumstrip 34 extends over the entire length of the bottom door rail 24 in aposition just above the floor, so that it will contact any objectscoming into the path of the door. This aluminum strip 34 is of generallyinverted L shape and has its top edge secured to the door by a pianohinge 36 so that the strip extends outwardly away from the door andthence downwardly so as to cover theplunger head 32. Pressure appliedalong any partof the strip 34 causes its lower edge to pivot toward thedoor, thus bringing the inner surface of the strip against the plungerhead 32 so as to drive the plunger 30 inwardly, thereby opening theswitch 18.

Electric leads 38 and 40 are connected to the switch terminals 44 and 46and extend through the hollow door rail to a position near the hingededge where they emerge and are suspended between the bottom door rail 24and a door jamb 48 so as to form a loose loop 50 to provide enough slackto prevent their being broken when the door 10 swings open. The wires 38and 40 extend from their position at the door jamb 48 to a convenientlocation in the power circuit as is seen n FIG. 3.

As illustrated in FIG. 3, the main power circuit for the pump unit 13 isconnected through a set of normally closed relay contacts 52 so that theentire power circuit is deenergized unless relay coil 54 is energized. fRelay coil 54 is connected to the power circuit by way of the normallyclosed contacts of safety switch 18, and thus the pump unit operatesnormally unless switch 18 is opened.

The operation of the safety device of the present invention may be verybriefly described as follows. Closing of the mat switch 14 will energizethe fluid pump which causes the door 10 to swing to its open position.As the swinging door 10 encounters an object, the foot of a child forinstance, the impact will force the aluminum strip 34 inwardly. Thisopens the safety switch 18 and shuts the inside of the bottom rail, asmall hole 60 may be drilled through which the switch can be inserted.This hole may be left open, or subsequently plugged, as desired. Fromthe above it will be seen that the safety switch of the presentinvention accomplishes all of the objectives set forth for it., It isapparent also that variations and substitutions may be made in thismechanism without departing from the spirit or scope of the invention.

For instance, switch 18 could be of the normally open type, in whichcase relay contacts 52 would be normally closed rather than normallyopen. Furthermore, if the rail 34 is not stiff enough to preventexcessive twisting if the impact is near the ends, two or more spacedswitches 18 may be used. In this event, the switches are wired in seriesif of the normally closed type, and in parallel if they are normallyopen. It is apparent, therefore, that the scope of the invention is tobe measured by the scope of the accompanying claim.

.States is:

Having described my invention, what I claim as new and useful and desireto secure by LettersrPatent of the United A-safety switch for. a poweroperated swinging door having a hollow bottom rail, comprising a switchsecured in the hollow bottom door rail, said'switch including anoutwardly biased switch actuating element extending outwardly throughthe door bottom rail on the exit side of the door, a rigid stripextending substantiallythe 'fullf width of the door on the exit sidethereof in a position adjacent the lower edge of the door, means hingingsaid strip to the door for pivoting movement of saidstrip about ahorizontal axis adjacent the upper edgeiof said" strip, said stripextending outwardly from said hinging, means and thence downwardly tocover said switch actuating element, said outwardl'y biased switchactuating elementimpinging against the inner surface of said strip,

and the lower edge of said stripwhen moved toward the door depressingsaid switch actuating element and actuat-.

ing said switch.

comes Mar. 13, 1928-

